Centrifugally armed fuze



Feb. 21, 1967 R. c. JOHNSON CENTRIFUGALLY ARMED FQZE 2 Sheets-Sheet 1 Filed April 16, 1965 INVENTOR RICHARD C. JOHNSON ATTORNEY Feb. 21, 1967 R. c. JOHNSON 3,304,866

CENTRIFUGALLY ARMED FUZE Filed April 16, 1965 2 51186138611881: 2

FIG. 2

INVENTOR.

RICHARD C. JOHNSON ATTORNEY Patented Feb. 21, 1967 3,304,866 CENTRIFUGALLY ARMED FUZE Richard C. Johnson, Hopkins, Minn., assignor to Honeywell Inc., Minneapolis, Minn., a corporation of Delaware Filed Apr. 16, 1965, Ser. No. 448,760 6 Claims. (Cl. 102--79) This invention relates generally to the art of munition fuzing and specifically concerns the design of a mechanical fuze for use in a rotating munition or projectile.

The designer of a munition fuze is faced with many design requirements that complicate his task. The fuze must be safe, reliable, inexpensive, small and easy to manufacture. Depending upon the application, one or more of these factors may take precedence over the others. Because these factors are not independent, however, it is difiicult to optimize one factor without adversely affecting the other factors. Too much emphasis on safety may result in a fuze that is too unreliable or too expensive to manufacture. On the other hand, too much emphasis on reliability may result in a fuze that is not safe from accidental detonation. The task of the designer is thus to optimize these factors without sacrificing any one of them.

The present invention successfully optimizes these factors into the design of a mechanical fuze. The fuze is highly reliable and safe, yet is not oversized or too difficult to manufacture. Reliability is achieved by utilizing a minimum number of moving parts, none of which are intricate or inherently difiicult to install, manufacture, or adjust. The fuze is highly safe in that only a rapid rotation about a normal spin axis can arm the fuze. Ordinary handling or accidental dropping will not effect arming. Even a series of shocks successively applied from different directions is not dangerous since the arming mechanism will not operate unless inertial forces are simultaneously applied in opposite directions; a situation occurring only when the munition is rapidly rotated about the spin axis. The present invention can therefore be utilized in a munition, such as a bomb or projectile, that rotates about a spin axis during flight to develop a centrifugal force that gradually decays during flight. The centrifugal force developed by the rotating munition initially releases the arming mechanism so that upon decay of the centrifugal force, the arming mechanism will place a detonator in line with a firing device. Upon impact, or other event, the firing device initiates the detonator in the usual fashion to explode the munition.

It is therefore an object of the present invention to provide a munition fuze responsive only to the rise and subsequent decay of centrifugal force developed about an axis of rotation of a rotating munition.

A further object of the present invention is to provide a reliable and safe munition fuze that utilizes an extremely small number of moving parts.

These and other objects of the invention will become apparent from the following specification and claims, and from the accompanying drawings, wherein:

FIGURE 1 is a top view of the preferred embodiment of the fuze shown in the safe condition and taken along a plane perpendicular to the spin axis of the fuze; and FIGURE 2 is a sectional side view taken along line 22 of FIGURE 1; and

FIGURE 3 is a similar sectional side view of the fuze in the armed position.

Referring now to FIGURE 1, there is disclosed a munition fuze having a cylindrical housing with a chamber 11 therein. Referring for a moment to FIG- URE 2, housing 110 is disclosed as having a pair of closed ends 12 and 13 at opposite ends of chamber 11. Housing 10 is designed to be mounted in a munition so that it will rotate with the munition about a spin axis 14.

Formed in end 12 concentric wit-h spin axis 14 is an opening 15 having a lead cup or booster charge 16 mounted therein. An opening 17 is formed in end 13 coaxially with opening 15. Mounted within opening .17 is a firing pin 18. Firing pin 18 has a first flange 19 formed adjacent the pointed end thereof to prevent firing pin 18 from being forced out of opening 17. A second flange 20 is connected to the opposite end of firing pin 18 by a screw 22. Mounted between flange 20 and end cover 13 is a coiled spring 21 that tends to hold firing pin 18 in the position shown in FIGURE 2.

A fulcrum pin 25 is mounted in chamber 11 along a line parallel to spin axis 14 but offset therefrom. Fulcrum pin 25 is mounted fixedly in end cover 12 so that it is immovable with respect to housing 10. Fulcrum pin 25 includes an enlarged heatd portion 26 that lies adjacent end cover 13.

Pivotally mounted for partial rotation about fulcrum pin 25 in chamber 11 is a first ar-m member or detonator arm 27. Detonator arm 27 is basically a three cornered carrier member. Formed in one corner of detonator arm 27 is an opening 28 through which extends fulcrum pin 25. Mounted within a second corner of detonator arm 27 is a detonator 29. Detonator 29 extends completely through detonator arm 27 as shown in FIGURE 3. Formed in the third corner of detonator arm 27 is a notch 30. A second portion 31 of notch 30 also extends beneath the surface of detonator arm 27 as shown in phantom in FIGURE 1 and as shown in FIGURE 2.

Detonator arm 27 is shown in the safe position in FIGURES l and 2. In the same position, detonator 29 is out of line with lead cup 16.

Also mounted for partial rotation about fulcrum pin 25 is a second arm member or locking plate 35. Formed at one end of locking plate 35 is an opening 36 through which extends fulcrum pin 25. Locking plate 35 is thus free to rotate about fulcrum pin 25 through a limited arc.

A torsion spring or biasing means 37 is mounted around fulcrum pin 25 between detonator arm 27 and locking plate 35. A first end 38 of spring 37 is curved around the side of detonator arm 27 to bias detonator arm 27 in a clockwise direction about pin 25 as shown in FIGURE 1. A second end 39 of spring 37 is curved around locking plate 35 to bias locking plate 35 in a counter clockwise direction about fulcrum pin 25 as shown in FIGURE 1.

Also mounted in chamber 11 adjacent detonator arm 27 is a latch member 45. Latch member 45 is an L-shaped member that is partially rotatable with a shaft 46. Latch member 45 is mounted in a slot 47 in housing member 10. Slot 47 is formed along a substantially radial line with respect to spin axis 14. Shaft 46 is mounted for rotation in a pair of openings formed in opposite walls of slot 47. Shaft 46 lies in a plane that is parallel to end covers 12 and 13 and also lies along a line that is generally perpendicular to a radial line extending from spin axis 14. As shown in FIGURE 2, latch member 45 has a lip portion 48 that extends into notch 31 in detonator arm 27.

With the fuze in the safe position as disclosed in FIG- URE 2, latch member 45 can not rotate with shaft 46 since lip portion 48 lies beneath detonator arm 27. Further, as shown in FIGURE 1, detonator arm 27 is prevented by latch member 45 from rotation in a clockwise direction. Latch member 45 thus prevents detonator arm 27 from rotating to a position in which detonator 29 is in line with lead cup 16.

Locking plate 35 has an end portion 50 that extends adjacent latch member 45 as shown in FIGURE 1 and FIGURE 2. End portion 50 also prevents rotation of latch member 45 from the position shown in FIGURE 1 and FIGURE 2. End portion 50 abuts a raised portion a of housing 10 to limit the rotation of locking plate 35 in a counterclockwise direction.

OPERATION In FIGURE 1 and FIGURE 2, the munition fuze is shown in the safe position. Detonator 29 is thus out of line with lead cup 16. If impact occurs with detonator arm 27 in this position, firing pin 18 will not be driven into detonator 29, thus no explosion of the munition can occur. Further, if detonator 29 should accidently explode, the explosion would not be transferred to lead cup 16 since they are offset a safe distance from each other.

In FIGURE 1, detonator arm 27 is shown in the safe position and locking plate 35 is shown in the locking position. Detonator arm 27 cannot move clockwise to the armed position since it abuts latch member 45. Latch member 45 cannot rotate out of the way since lip portion 48 lies beneath detonator arm 27. Further, end portion 50 of locking plate 35 abuts latch member 45 to prevent movement thereof.

When the munition is launched and begins to rotate about spin axis 14, centrifugal force is applied to detonator arm 27, to locking plate 35 and to latch member 45. When the spin rate reaches a certain level, the centrifugal force acting on detonator arm 27 is sufficient to overcome the biasing effect of spring 37 so that detonator arm 27 rotates in a counter clockwise direction to a release position. In the release position, notch 30 of detonator arm 27 clears lip portion 48 of latch member 45. At the same time, the centrifugal force acting on locking plate causes locking plate 35 to rotate in a clockwise direction against spring 37 until it reaches a release position in which end portion 50 no longer abuts latch member 45. At this point, latch member is no longer restrained in the first position shown in FIGURES l and 2 by either detonator arm 27 or end portion 50. Latch member 45 is constructed so that the centrifugal force of the rotating munition will cause it to rotate with shaft 46 to the position shown in FIGURE 3. Latch member 45 is then no longer in position to prevent clockwise rotation of detonator arm 27.

When the spin rate of the munition begins to decay, the centrifugal force being developed is no longer sufficient to overcome the bias of torsion sprin 37. Spring 37 then forces detonator arm 27 to rotate in a clockwise direction to an armed position in which detonator 29 is in line with lead cup 16. Locking plate 35 returns to its original position against ledge 10a in housing 10. Latch member 45 stays in the armed or tipped out position. When impact occurs, firing pin 18 is driven into detonator 29 to in turn cause ignition of lead cup or booster charge 16.

Detonator arm 27 is thus held normally in a safe position by spring 37 and by latch member 45. Latch member 45 is itself held in a first position by detonator arm 27 and by locking plate 35. Locking plate 35 is held in the locking position by spring 37.

The subject invention is extremely safe during even rough handling since the fuze will arm only when subjected to a predeterminer rotation about the spin axis with subsequent decay. Normal dropping of the fuze in any direction will cause only one of the movable members to rotate. All three must rotate before the fuze will arm, however.

A model of this fuze has been tested according to military specifications. These tests revealed that no single impact or any combination of successive impacts could cause arming of the fuze. At least one of the three movable members will always remain in the safe position to prevent arming of the fuze. It must be remembered that the fuze must be rotated at a predetermined rate about the spin axis so that all movable members will rotate outwardly. Until this occurs, the detonator arm cannot move to the armed position.

This arming mechanism can be used in any environment where application andsubsequent attenuation of rotational energy is available. The size of the device is limited only by the separation required between the detonator and the lead cup to maintain a safe condition should the detonator be accidently fired. The arming mechanism can be used with stab detonators or delay type detonators of all common sizes, and with primers for pyrotechnic systems. All standard types of firing mechanisms can be used. The spring biased firing pin disclosed in the preferred embodiment is intended to be illustrative only and could easily be replaced by any well known firing mechanism. The speed of arming of this device can also be varied by adjusting the strength of torsion spring 37. Tests have revealed that the arming speed is repeatable and consistent.

Theparticular configuration of the various movable elements used in the preferred embodiment are not critical. Generally speaking, the movable members must be mounted eccentrically with respect to the spin axis in order to achieve operation. Each of three movable members must be responsive to the centrifugal force to move outwardly to thereby release one of the other members.

From the above description it will be apparent that I have invented a munition fuze having new and more effective means for utilizing the centrifugal force developed by a rotating munition for arming purposes and providing safety in handling. Although the form of the invention described herein constitutes a preferred embodiment, it will be understood that changes may be made within the spirit of the invention limited only by the scope of the appended claims.

I claim as my invention:

1. A fuze for a rotating munition, comprising:

(a) a housing having a cylindrical chamber therein with first and second closed ends, said ends each having a single axial opening formed therein;

(b) a fulcrum pin mounted in said chamber at a fixed distance from said openings having an axis parallel to a line extending through said axially aligned openmgs;

(c) a detonator arm mounted for partial rotation about said fulcrum pin through safe, release, and arm positions;

(d). a latch member mounted in said chamber adjacent said detonator arm for rotation from a first to a second position about an axis lying in a plane generally parallel to said ends and along a line generally perpendicular to a radial line extending from said fulcrum pin, said latch member in said first position having a portion thereof abutting said detonator arm to prevent said detonator arm from rotating to said armed position, said latch member further having a lip portion formed thereon extending between said detonator arm and said first end in said first position to prevent rotation of said latch member;

(e) a locking plate mounted for partial rotation about said fulcrum pin between release and locking positions, said locking plate in said locking position having a portion thereof abutting said latch member to prevent rotation of said latch member from said first position;

(f) a coiled spring mounted between said locking plate and said detonator arm to normally hold said locking plate in said locking position and said detonator arm in said safe position;

(g) an explosive lead cup mounted in said opening in said first end;

(h) a detonator mounted in said detonator arm in line with said lead cup in said armed position; and

(i) a firing pin mounted in said opening in said second end, said locking plate and said detonator arm being rotated to said release positions by the centrifugal force developed by said rotating projectile to thereby release said latch member, said latch member being subsequently rotated to said second position by the centrifugal force, said detonator arm being rotated to said armed position by said coiled spring upon the decay of said centrifugal force to place said detonator in line with said firing pin and said lead cup.

2. A fuze for a rotating projectile, comprising:

(a) a housing having a chamber therein with first and second closed ends;

(b) a fulcrum pin mounted in said chamber;

(c) a detonator arm mounted for partial rotation about said fulcrum pin through release, safe, and armed positions;

(d) a latch member mounted in said chamber ad acent said detonator arm for rotation from a first to a second position, said latch member in said first position having a portion thereof abutting said detonator arm to prevent said arm from rotating to said armed position, said latch member further having a'lip portion formed thereon underlying said detonator arm in said safe position to prevent rotation of sa1d latch member from said first position;

(e) a locking plate mounted for partial rotation about said fulcrum pin between release and locking positions, said locking plate in said locking position having a portion thereof abutting said latch member to prevent rotation of said latch member from said first position;

(f) spring means mounted between said locking plate and said detonator arm to normally hold said locking plate in said locking position and said detonator arm in said safe position;

(g) an explosive lead cup mounted in said first end;

(h) a detonator mounted in said detonator arm in line with said lead cup in said armed position; and

(i) firing pin means mounted in said second end, said locking plate and said detonator arm being rotated to said release positions by the centrifugal force developed by said rotating projectile to thereby release said latch member, said latch member being subsequently rotated to said second position by the centrifugal force, said detonator arm being rotated to said armed position by said spring means upon the decay of said centrifugal force to place said detonator in line with said firing pin and said lead cup.

3. A fuze for rotating projectile, comprising:

(a) a housing having a chamber therein;

(b) a pin mounted in said chamber;

(c) a first arm member mounted for partial rotation about said pin through safe, release, and armed positions;

((1) a latch member mounted in said chamber adjacent said first arm member for rotation from a first to a second position, said latch member in said first position having a portion thereof abutting said first arm member to prevent said first arm member from rotating to said armed position, said latch member further having a lip portion formed thereon underlying said first arm member in said safe position to prevent rotation of said latch member from said first position;

(e) a second arm member mounted for partial rotation about said pin between release and locking positions said second arm member in said locking position having a portion thereof abutting said latch member to prevent rotation of said latch member from said first position;

(f) biasing means mounted between said first arm member and said second arm member to bias said first arm member toward said armed position and said second arm member toward said locking position;

(g) a detonator mounted in said first arm member;

and

(h) firing pin means mounted in said chamber, said first and second arm members being rotated to said release positions by the centrifugal force developed by said rotating projectile to thereby release said latch member, said latch member being subsequently rotated to said second position by the centrifugal force, said first arm member being rotated to said armed position by said biasing means upon the decay of said centrifugal force to place said detonator in line with said firing pin.

4. A fuze for rotating projectile, comprising:

(a) a housing having a chamber therein;

(b) a detonator arm mounted in said chamber for partial rotation about an eccentric axis through release, safe, and armed positions;

(c) a latch member mounted in said chamber adjacent said detonator arm for movement from a first position abutting said detonator arm to a second position, said latch member in said first position preventing said detonator arm from rotating to said armed position;

(d) a locking plate mounted in said chamber for partial rotation about said eccentric axis between release and locking positions, said locking plate in said locking position having a portion thereof abutting said latch member to prevent movement of said latch member from said first position;

(e) biasing means connected to said locking plate and said detonator arm to normally hold said locking plate in said locking position and said detonator arm in said safe position;

(f) a detonator mounted in said detonator arm; and

(g) firing pin means mounted in said chamber, said locking plate and said detonator arm being rotated to said release positions by the centrifugal force devel oped by said rotating projectile to thereby release said latch member, said latch member being subsequently moved to said second position by the centrifugal force, said detonator arm being rotated to said armed position by said biasing means upon the decay of said centrifugal force to place said detonator in line with said firing pin.

5. A fuze for a munition subject to rotational forces after launch, comprising:

(a) a housing;

(b) a first eccentrically mounted arm member mounted in said housing to rotate outwardly in a first direction in response to the centrifugal forces developed by the rotating munition, said first arm member being rotatable outwardly from an armed position through a safe position to a release position;

(c) latching means mounted in said housing to abut said first arm member in a first position to prevent said first arm member from rotating to said armed position, said latching means being movable outwardly to a second position in response to the cen- Lrifugal force to thereby release said first arm mem- (d) a second eccentrically mounted arm member mounted in said housing to rotate outwardly in a second direction generally opposite said first direction in response to the centrifugal forces, said second arm member being rotatable outwardy from a locking position to a release position, said second arm member in said locking position abutting said latchingmeans to hold said latching means in said first position;

(e) means for biasing said first arm member toward said armed position;

(f) means for biasing said second arm member toward said locking position;

(g) detonator means mounted in said first arm member; and

(h) initiating means mounted in said housing, said first arm member rotating from said safe to said release positions in response to the centrifugal force, said second arm member rotating from said locking position to said release position in response to the centrifugal force to thereby release said latching 7 8 means for movement to said second position, said (e) biasing means mounted in said housing to bias said biasing means driving said first arm member from first arm member toward said armed .position and said release position to said armed position upon the said second arm member toward said locking posidecay of said centrifugal force to thereby position tion; said detonator means in an operative posiiton with (f) detonating means mounted in said first arm memrespect to said initiating means. ber; and 6. A fuze for a munition subject to rotational forces (g) initiating means mounted in said housing, said after launch, comprising: first and second arm members being rotated to said (a) a housing; release positions by the centrifugal force developed (b) afirst eccentrically mounted arm member mounted 10 by said rotating munition to thereby release said for partial rotation in said housing through release, latching means, said latching means being substansafe, and armed positions; tially moved to said second position by the centrifu- (c) latching means mounted in said housing adjacent gal force, said first arm member being rotated to said said first arm member for movement from a first to armed position by said biasing means upon the decay a second position in response to the centrifugal force of said centrifugal force to place said detonator in developed by the rotating munition, said latching line with said initiating means. means in said first position abutting said first arm member in said safe position to prevent said first arm References Cited by the Examiner member from rotating to said armed position; UNITED STATES PATENTS (d) a second eccentrically mounted arm member mounted for partial rotation in said housing between 214461545 8/1948 Mccas hn 1O2 80 release and locking positions, said second arm mern- 3,117,522 1/1964 Hutchlson et 1O2 79 X her in said locking position abutting said latching means to prevent movement of said latching means BENJAMIN BORCHELT Prlmmy Exwmner' from said first position; G. H. GLANZMAN, Assistant Examiner. 

6. A FUZE FOR AW MUNITION SUBJECT TO ROTATIONAL FORCES AFTER LAUNCH, COMPRISING: (A) A HOUSING; (B) A FIRST ECCENTRICALLY MOUNTED ARM MEMBER MOUNTED FOR PARTIAL ROTATION IN SAID HOUSING THROUGH RELEASE, SAFE, AND ARMED POSITIONS; (C) LATCHING MEANS MOUNTED IN SAID HOUSING ADJACENT SAID FIRST ARM MEMBER FOR MOVEMENT FROM A FIRST TO A SECOND POSITION IN RESPONSE TO THE CENTRIFUGAL FORCE DEVELOPED BY THE ROTATING MUNITION, SAID LATCHING MEANS IN SAID FIRST POSITION ABUTTING SAID FIRST ARM MEMBER IN SAID SAFE POSITION TO PREVENT SAID FIRST ARM MEMBER FROM ROTATING TO SAID ARMED POSITION; (D) A SECOND ECCENTRICALLY MOUNTED ARM MEMBER MOUNTED FOR PARTIAL ROTATION IN SAID HOUSING BETWEEN RELEASE AND LOCKING POSITIONS, SAID SECOND ARM MEMBER IN SAID LOCKING POSITION ABUTTING SAID LATCHING MEANS TO PREVENT MOVEMENT OF SAID LATCHING MEANS FROM SAID FIRST POSITION; (E) BIASING MEANS MOUNTED IN SAID HOUSING BIAS SAID FIRST ARM MEMBER TOWARD SAID ARMED POSITION AND SAID SECOND ARM MEMBER TOWARD SAID LOCKING POSITION; (F) DETONATING MEANS MOUNTED IN SAID FIRST ARM MEMBER; AND (G) INITIATING MEANS MOUNTED IN SAID HOUSING, SAID FIRST AND SECOND ARM MEMBERS BEING ROTATED TO SAID RELEASE POSITIONS BY THE CENTRIFUGAL FORCE DEVELOPED BY SAID ROTATING MUNITION TO THEREBY RELEASE SAID LATCHING MEANS, SAID LATCHING MEANS BEING SUBSTANTIALLY MOVED TO SAID SECOND POSITION BY THE CENTRIFUGAL FORCE, SAID FIRST ARM MEMBER BEING ROTATED TO SAID ARMED POSITION BY SAID BIASING MEANS UPON THE DECAY OF SAID CENTRIFUGAL FORCE TO PLACE SAID DETONATOR IN LINE WITH SAID INITIATING MEANS. 